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Full-Text Articles in Physics

Long-Time Electron Spin Storage Via Dynamical Suppression Of Hyperfine-Induced Decoherence In A Quantum Dot, Wenxian Zhang, N. P. Konstantinidis, V. V. Dobrovitski, B. N. Harmon, Lea F. Santos, Lorenza Viola Mar 2008

Long-Time Electron Spin Storage Via Dynamical Suppression Of Hyperfine-Induced Decoherence In A Quantum Dot, Wenxian Zhang, N. P. Konstantinidis, V. V. Dobrovitski, B. N. Harmon, Lea F. Santos, Lorenza Viola

Dartmouth Scholarship

The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large interpulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance …


Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff Jan 2008

Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff

Physics Faculty Research and Publications

Dynamic micromagnetic simulation studies have been completed to observe the motion of a domain wall in a magnetic nanowire in an effort to increase the field-driven domain wall speed. Previous studies have shown that the wire dimensions place a cap on the maximum speed attainable by a domain wall when driven by a magnetic field placed along the direction of the nanowire. Here we present data showing a significant increase in the maximum speed of a domain wall due to the addition of a magnetic field placed perpendicular to the longitudinal driving field. The results are expressed in terms of …


The Biot-Savart Law: From Infinitesimal To Infinite, Jeffrey A. Phillips, Jeff Sanny Jan 2008

The Biot-Savart Law: From Infinitesimal To Infinite, Jeffrey A. Phillips, Jeff Sanny

Physics Faculty Works

In this paper, we discuss a simple apparatus and accompanying class activity that we have developed to illustrate the Biot-Savart law. Since students in introductory electricity and magnetism courses often find this law a mathematical mystery, we feel that a simple experiment such as this will provide the students a better understanding of the concepts introduced. By collecting data from several finite segment lengths, students are able to infer the 1/r2 distance dependence of the magnetic field for infinitesimal segments and the 1/r dependence for infinite wires.


Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya Jan 2008

Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya

Faculty Publications

A high-throughput high-sensitivity optical technique for measuringmagnetostriction of thin-film composition-spread samples has been developed. It determines the magnetostriction by measuring the induced deflection of micromachined cantilever unimorph samples. Magnetostrictionmeasurements have been performed on as-deposited Fe–Ga and Fe–Ga–Al thin-film composition spreads. The thin-film Fe–Ga spreads display a similar compositional variation of magnetostriction as bulk. A previously undiscovered peak in magnetostriction at low Ga content was also observed and attributed to a maximum in the magnetocrystalline anisotropy. Magnetostrictive mapping of the Fe–Ga–Al ternary system reveals the possibility of substituting up to 8at.%Al in Fe70Ga30 without significant degradation of magnetostriction.